This invention generally relates to motor vehicle air bags. More particularly, the invention relates to an air bag module having a shroud that influences the deployment characteristics of the air bag to reduce the risk of injury to an out-of-position occupant.
Many air bag systems are designed to protect a 50th percentile, unbelted male occupant in a 48 Kph (30 mph) crash. As the air bag is designed to protect the occupant during a relatively severe crash the air bag must be inflated at a relatively aggressive rate. This rate of inflation may not be optimum for a smaller sized occupant and/or one seated close (out-of-position) to the location of the air bag. Recently, a new type of air bag system has been proposed (a smart system) that uses a multi-stage inflator, as well as occupant and crash sensors. In these smart systems the rate of inflation is varied in accordance with parameters which include occupant size, crash conditions, seating position, etc. As can be appreciated these smart systems are costly, unfortunately not in production and complicated.
Further, in many prior art systems, the air bag is designed to deploy from the module directly at the chest of the occupant. This type of deployment characteristic may result in high chest and neck forces being exerted on these body areas.
It is an object of the present invention to provide an air bag that is usable in both a conventional and an advanced air bag system. A further object of the invention is to provide an air bag and air bag module which reduce the potential of injury for an out-of-position (OOP) occupant. An additional object of the present invention is to provide an air bag that protects the OOP occupant while not sacrificing protection for the 50th percentile male occupant. An additional object of the present invention is to maximize ease of manufacture while reducing overall cost (of the air bag and air bag module). A further object of the invention is to provide an air bag that impacts the occupant""s torso at a downward angle lessening initial bag/occupant impact forces.
A conventional air bag module is typically mounted upon a motor vehicle""s steering wheel or in the instrument panel of the vehicle. The typical module will most often include a mounting plate or housing that facilitates the mounting of the module to the adjacent portion of the vehicle and provides a reaction surface for deployment forces. The modules will also include a single or multi-level inflator that is mounted to the mounting plate, and an air bag located proximate the inflator to receive inflation gas. The air bag is protected by a cover that is forced open as the air bag inflates.
The prior art has shown internal deployment flaps, which utilize steel bands or stitched deployment sheets to redirect the energy of the deploying air bag when an out-of-position occupant is in close proximity to the air bag module (see U.S. Pat. Nos. 5,004,266 and 5,498,030).
Accordingly, the invention comprises: an air bag module and more particularly a shroud which envelops an air bag and is secured to portions of a mounting plate or housing. The air bag is inflated by an inflator and protected by a cover. In the preferred embodiment of the invention the shroud is made from a relatively flexible fabric and is situated about the air bag. The shroud limits the air bag""s forward extension during the early stages of deployment. In one embodiment, the shroud includes an open end while in another embodiment the shroud has an enclosed end that is torn open.
The invention further includes a method for producing an air bag module assembly as well as a method of changing the kinematics of a cushion deploying from within the module when-an object of sufficient mass is near the module.
While a preferred embodiment of the module has been described in detail, it should be apparent that many modifications and variations hereto are possible, all of which fall within the true spirit and scope of the invention. Many objects and purposes of the invention shall be clear from the following detailed description of the drawings.